LXR linux/drivers/video/backlight/ep93xx

   1/*
   2 * Driver for the Cirrus EP93xx lcd backlight
   3 *
   4 * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 * This driver controls the pulse width modulated brightness control output,
  11 * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
  12 */
  13
  14#include <linux/module.h>
  15#include <linux/platform_device.h>
  16#include <linux/io.h>
  17#include <linux/fb.h>
  18#include <linux/backlight.h>
  19
  20#define EP93XX_MAX_COUNT                255
  21#define EP93XX_MAX_BRIGHT               255
  22#define EP93XX_DEF_BRIGHT               128
  23
  24struct ep93xxbl {
  25        void __iomem *mmio;
  26        int brightness;
  27};
  28
  29static int ep93xxbl_set(struct backlight_device *bl, int brightness)
  30{
  31        struct ep93xxbl *ep93xxbl = bl_get_data(bl);
  32
  33        writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
  34
  35        ep93xxbl->brightness = brightness;
  36
  37        return 0;
  38}
  39
  40static int ep93xxbl_update_status(struct backlight_device *bl)
  41{
  42        int brightness = bl->props.brightness;
  43
  44        if (bl->props.power != FB_BLANK_UNBLANK ||
  45            bl->props.fb_blank != FB_BLANK_UNBLANK)
  46                brightness = 0;
  47
  48        return ep93xxbl_set(bl, brightness);
  49}
  50
  51static int ep93xxbl_get_brightness(struct backlight_device *bl)
  52{
  53        struct ep93xxbl *ep93xxbl = bl_get_data(bl);
  54
  55        return ep93xxbl->brightness;
  56}
  57
  58static const struct backlight_ops ep93xxbl_ops = {
  59        .update_status  = ep93xxbl_update_status,
  60        .get_brightness = ep93xxbl_get_brightness,
  61};
  62
  63static int ep93xxbl_probe(struct platform_device *dev)
  64{
  65        struct ep93xxbl *ep93xxbl;
  66        struct backlight_device *bl;
  67        struct backlight_properties props;
  68        struct resource *res;
  69
  70        ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
  71        if (!ep93xxbl)
  72                return -ENOMEM;
  73
  74        res = platform_get_resource(dev, IORESOURCE_MEM, 0);
  75        if (!res)
  76                return -ENXIO;
  77
  78        /*
  79         * FIXME - We don't do a request_mem_region here because we are
  80         * sharing the register space with the framebuffer driver (see
  81         * drivers/video/ep93xx-fb.c) and doing so will cause the second
  82         * loaded driver to return -EBUSY.
  83         *
  84         * NOTE: No locking is required; the framebuffer does not touch
  85         * this register.
  86         */
  87        ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
  88                                      resource_size(res));
  89        if (!ep93xxbl->mmio)
  90                return -ENXIO;
  91
  92        memset(&props, 0, sizeof(struct backlight_properties));
  93        props.type = BACKLIGHT_RAW;
  94        props.max_brightness = EP93XX_MAX_BRIGHT;
  95        bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
  96                                        ep93xxbl, &ep93xxbl_ops, &props);
  97        if (IS_ERR(bl))
  98                return PTR_ERR(bl);
  99
 100        bl->props.brightness = EP93XX_DEF_BRIGHT;
 101
 102        platform_set_drvdata(dev, bl);
 103
 104        ep93xxbl_update_status(bl);
 105
 106        return 0;
 107}
 108
 109#ifdef CONFIG_PM_SLEEP
 110static int ep93xxbl_suspend(struct device *dev)
 111{
 112        struct backlight_device *bl = dev_get_drvdata(dev);
 113
 114        return ep93xxbl_set(bl, 0);
 115}
 116
 117static int ep93xxbl_resume(struct device *dev)
 118{
 119        struct backlight_device *bl = dev_get_drvdata(dev);
 120
 121        backlight_update_status(bl);
 122        return 0;
 123}
 124#endif
 125
 126static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
 127
 128static struct platform_driver ep93xxbl_driver = {
 129        .driver         = {
 130                .name   = "ep93xx-bl",
 131                .pm     = &ep93xxbl_pm_ops,
 132        },
 133        .probe          = ep93xxbl_probe,
 134};
 135
 136module_platform_driver(ep93xxbl_driver);
 137
 138MODULE_DESCRIPTION("EP93xx Backlight Driver");
 139MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 140MODULE_LICENSE("GPL");
 141MODULE_ALIAS("platform:ep93xx-bl");
 142